The present invention concerns an interlacing apparatus and process for the interlacing of multifilament yarns in accord with the generic concept of using a flow of a medium through a specially designed jet nozzle to entwine multifilament yarns.
Interlacing apparatuses and processes of the kind discussed here, have been brought into common knowledge by DE 37 11 759 C2. The apparatus and process serve to improve the integrity of the filaments of the multifilament yarns and thereby better their further workability. The reason for this is that the single multifilament yarn, which is comprised of substances which are preferably thermoplastic or other material, upon being fed to the interlacing apparatus is yet untwisted or possesses only a minimum protective twist, which still has insufficient integrity for further processing. The required integral strength is obtained by the multifilament yarn only by the interlacing of its filaments. By means of the interlacing apparatus, the filaments of several multifilament yarns can be commonly intertwined into one unified multifilament yarn.
The interlacing quality, or the outcome of the interlacing, is characterized by certain points. The plaiting/interlacing tendencies of the filaments and also the spacing lying between the said intertwined filaments define these points. Within these points, the possibility exists for essentially non-entwined or open places in the yarn. When an interlacing of the multifilament yarn occurs, in addition a very weak interlacing can be achieved, in which no interlacing points arise. In this situation, only a light, scarcely visible commingling of the filaments takes place. Such yarns exhibit only a small degree of thread closure and without additional expensive measures, cannot be subjected to further processes such as imparting twist, spindle whorling or finishing. At the most, these yarns can only be further worked under certain limiting conditions.
"Thread closure" is a customary designation for the compactness of multifilament yarns and describes the integrity, i.e. the cohesiveness of the filaments.
The known interlacing apparatus possesses a yarn conduit through which a multifilament yarn passes which has a plurality of filaments. As this takes place, the filaments are commingled by means of an air flow issuing from a jet nozzle opening. The jet nozzle exhibits normally a circular or elliptically shaped cross-section, which is designed symmetrically to the longitudinal axis of the yarn conduit. In many cases, the commingling of the filaments of the multifilament yarn from this apparatus does not result in a desirable degree of interlacing. The multifilament yarn exhibits irregularities, for example lengthy, faulty stretches, which indicate unentwined yarn portions. Further processing of the multifilament yarn, for instance weaving, tufting, knitting, or sewing, leads to damage to these open, unprotected yarn stretches. Single filaments break and open out, whereby a thread breakage or break in neighboring threads and/or faults in textile surface formation occurs.